Electronic sensors generally measure a physical quantity and convert the measured physical quantity into a signal that is provided to an electronic instrument (e.g., integrated chip processor). In recent years, the number of areas using sensors has vastly expanded. For example, sensors can be found in diverse applications such as chemical agent detection units, medical diagnostic equipment, industrial process controls, pollution monitoring, automobiles, etc.
Infrared sensors such as for instance mid-infrared (MIR) sensors measure radiation emitted in the infrared (IR) portion of the electro-magnetic spectrum from objects having a temperature above absolute zero. The mid-infrared spectrum covers electromagnetic radiation with wavelengths in a range of approximately 2-25 μm. By measuring changes in the MIR spectrum, sensors are able to measure changes in a sample's chemistry or temperature, for example.
The reduction of the optical path length (millimeter and centimeter-range today) is one central tasks on the way to monolithically integrated IR sensors. One promising approach is the application of evanescent surface fields in waveguides of sub-wavelength diameters. To take full advantage of this concept, an efficient collimation and coupling of infrared light into a fiber as well as an excellent thermal isolation of a light emitter is desired.